The Obama administration's decision to shelve its missile defence plans for eastern Europe represents an attempt to cut through some of the knots that have long held back progress on a range of critical global concerns.

Those concerns are closely entwined. Lack of progress on one front is paralysing movement on others. The prospect of interceptor missiles in Poland and a radar system in the Czech Republic was a constant irritant in negotiations with Russia over a new arms control treaty, to replace Start (Strategic arms reduction treaty) which expires in early December. Russia sees missile defence as a deliberate attempt to undermine its own nuclear deterrent, not as a defensive measure against Iran, as Washington claims.

Glitches in the Start Plus talks spilled over into UN security council discussions over a new resolution on disarmament and non-proliferation due to go before a vote at a special summit session chaired by Barack Obama next Thursday. Obama wanted the council's permanent five members – the US, Russia, Britain, China and France – to make a bold statement of intent on reducing the number of nuclear weapons in their arsenals, but progress in those discussions has been blocked in the past few days by Russia and China.

Even more importantly, Russia is leading resistance to the imposition of further punitive sanctions on Iran for its defiance of security council demands for the suspension of uranium enrichment. Tehran says it is enriching uranium for civil power generation but the west, and Israel, allege it is for warheads.

Russian resistance, backed by China, severely weakened the sanctions threat. Iran is due to meet the major powers on October 1 for wide-ranging discussions but its government has repeatedly insisted it will not negotiate on its nuclear programme.

That impasse is exacerbating tensions across the Middle East. Arab countries are considering going nuclear themselves. Meanwhile, Israel is defying US pressure to halt settlement-building, using it in part as a bargaining chip to get tough action on Iran. The settlement construction endangers an American plan to restart talks with the Palestinians with a meeting between Binyamin Netanyahu and Mahmoud Abbas on the margins of next week's UN meeting.

The urgency of these converging timetables explains the timing of the surprise US move. It is a huge gamble for Obama as it will provoke uproar among his domestic opponents and damage him if he fails to demonstrate clear strategic gains.

But he had little choice. His ambitious global agenda was facing paralysis.

Much will now depend on the Russian response. If the Kremlin pockets this victory and digs in further in the hope of forcing more concessions, it will come to nothing.

If it takes the gesture as an opening to a more co-operative relationship with the US, progress could come quickly. A tougher Russia in multilateral talks in Iran could shock Tehran into compromise. That could be used as a lever on the Israelis, which could kick-start the Middle East peace process.

The abandonment of east European missile defence also clears the way for much deeper cuts in US and Russian nuclear arsenals in successor treaties to Start, and that would win goodwill from the non-weapons states when it comes to the attempted repair of the non-proliferation treaty next May.

The ball is now in Moscow's court. It has a strategic interest in preventing a nuclear arms race on its southern border, but a tactical interest in frustrating US foreign policy. Until now it has chosen tactical advantage over long-term but uncertain strategic gains. It matters enormously for a lot of reasons, what Moscow chooses to do now.